The invention relates generally to an opto-electronic device comprising at least one sulfonated aromatic condensation copolymer or at least one phosphonated aromatic condensation copolymer.
Opto-electronic devices, such as organic light emitting devices (OLEDs), which make use of thin film materials that emit light when subjected to a voltage bias, are expected to become an increasingly popular form of flat panel display technology. This is because OLEDs have a wide variety of potential applications, including cell phones, personal digital assistants (PDAs), computer displays, informational displays in vehicles, television monitors, as well as light sources for general illumination. Due to their bright colors, wide viewing angle, compatibility with full motion video, broad temperature ranges, thin and conformable form factor, low power requirements and the potential for low cost manufacturing processes, OLEDs are seen as a future replacement technology for cathode ray tubes (CRTs) and liquid crystal displays (LCDs). Due to their high luminous efficiencies, OLEDs are seen as having the potential to replace incandescent, and perhaps even fluorescent, lamps for certain types of applications.
State-of-the-art OLEDs are built on a transparent anode, typically indium tin oxide (ITO). The ITO is a degenerated n-type semiconductor with a work function in the range of 4.4 to 4.8 eV. However, for most organic emissive materials (OEMs) such as light-emitting polymers (LEPs), the highest occupied molecular orbital (HOMO) lies more than 5 eV below vacuum. A significant energy barrier for hole injection is thus expected at the ITO/OEM interface, resulting in inefficient hole injection and subsequently poor overall device performance such as poor quantum efficiency and high driving voltages. Notwithstanding the current efforts to circumvent this problem of inefficient hole injection, there exists a need in the art to develop a single-component and, more preferred, organic solvent-based, hole-injection material.